Method and apparatus for wireless telephony.



J. P. MCCARTY & K. DOUGLAS.

METHOD AND APPARATUSEFOR WIRELESS TELEPHONY. APPLKCATION mu) MAR. 1912, RENEW EDSEP T.30,1916.

1,265,365. Patented N 21, 1916.

' VJMVENTORS.

Q WITNESSES:

ATTORNEY.

UNITED sTATEs PATENT OFFICE.

OHN r. MQGARTY, F OAKLAND,'AND KENDALL DOUGLAS, OF SAN FRANCISCO,

oALIEo NI ssIGNoEs, BY MESNE ASSIGNMENTS, TO

UNIVERSAL WIRELESS TELEPHONE AND" TELEGRAPH COMPANY, OF LQS-AN 'GELES,CALIFORNIA, A COR- PORATION 0] CALIFORNIA.

METHOD AND APPARATUS FOR WIRELESS TELEPHONY.

Application filed March 6,1912, Serial No'. 682,016.

To all whom it may concern 7 Be itknown that we, JOHN P. MoCAnrY,

of the city of Oakland, countyof Alameda,

State ofCa-lifornia, and KEXDALL DoUc LAS, ofthe city and county ofSan Francisco, .State of Callfornia.

both citizens of the Unlted States, have invented certain new .and useful Improvements in Methods and Apparatus for Wireless Telephony, of which the following is a specification.

. Our invention relates to the art, of wireless telephony and especially to that branch of theart known'as spark telephony.

Attempts to use the spark system for telephonic transmission have hitherto met with failure unless enormously high frequency alternators were employed, and such alternators are exceedingly expensive, of low efiiciency, and for many reasons impracticable.

The primary object of our invention is to provide a new and useful method and api paratus for spark telephony, using comparatlvely, very low frequency alternating currents.

We have discovered that spark produced damped waves of comparatively, very low alternating frequency maybe used for.

telephony, if said waves'be suppressed during the moment of silence, and emitted rectly in correspondence with speech waves.

It is the object of our invention to provide a new and useful method and apparatus embodying our discovery, for transmitting speech by wireless telephony, wherein,

although using continually produced oscillations, damped or undamped, there shall be effective radiation only during the time of vocal vibrations; and with the said object in view, our invention consists in continually producing oscillations in anoscillation circuit, suppressing the radiation in an associated radiationcircuit, and directly radiating energyby operating the microphone transmitter. 1

It also consists in apparatus for continually producing oscillations in an oscillation circuit, for suppressing IZIClIELtIOIIIH an associated radiation circuit, and for directly radiating energy by operatmg a m1- crophone transmitter. It also consists in a method of transmitting speech by wireless telephony, by con- Specification of Letters Patent.

Renewed September 30, 1916. Serial No. 123,197.

tinually producing oscillations in an oscillation c rcuit, suppressing the radiation in an associated radiatlon circuit, and emitting .radiative energy in waves directly correenergy, and

spending in rate ofemission, form, with the pitch, force and quality of speech waves. I It also consists in apparatus for practising said method. i

It also consists in the novel parts, combinations and arrangements set forth in the following specification, particularly pointed out in the claims, and illustrated in the accompanying drawing, of which l igure 1 is a diagrannnatlc view of a transmitting wireless telephone system, showing the 1n1t1al arrangement of apparatus, with, transmitter branch of radiation circuit open; and greatest radiation occur-' ring; Fig. 2' is a similar View, showing the second step in arranging our apparatus, the transmitter branch of. radiation circuit.

closed, the transmitter npn-operated and radiation suppressed. 1 F g. 3 is a similar view, showinga third conldition, in which the (transmitter is operated and in which 7). the variable capacity 4,1and the ground A branch (1 of the radiation circuit provided, which is grounded at one end 6, and contains a telephone transmitter T, which may consist of one 7 or more microphone transmitters. I

In Fig. 1 the branch circuit is shown as open at 7 and closed in the other figures. An

Patented Nov. 21, 1916.

ammeter 8 in the antenna is shown to indicate the change of radiation under theva rious conditions. An oscillation circuit (Z is associated with the radiation circuit 111 any well known manner, as though the. oscillation transformer b by its connection with primary 9; and it also contains the spark gap 8, variable condensers 10, and the sec ondary 11 of the transformer f. The condensers are shown as connected in multiple series instead of as a single equivalent ad- 'justable condenser because the former arrangement tends to prevent the destructive flashing over between plates which is likely to occur under high pressure. An alternator circuit it includes the source of alternating current 12, which "is one of comparatively very low frequency, and primary 13 of transformer f. p

.In practising our method, we first place our apparatus in the condition illustrated in Fig. 1, with the branch 0 open. lVe then tune the oscillation circuit (Z and radiation circuit ainto complete syntony with each other, so that the maximum radiation is taking place, as indicated by the needle of the ammeter in Fig. 1. When the state of syntony is attained we close branch 0, as shown in Fig. 2; whereupon, not only is the Iildit tion circuit, including its branch, thrown out of tune with the oscillation circuit (1, a condition which tends to suppress radiation, but whatever oscillations are created are practically confined in the closed circuit formed by the coils 2 and 3. the condenser 4 and branch c, wherefore they are denominated suppressed radiation. Fnder conditions the needle of the .annneter approximates zero, which indicates that the eti'ective radiation is suppressed. Such condition is maintained during the moments of silence.

Referring now to Fig. 3, when talking occurs. radiative energy is emitted, as shown by the ammeter in the antenna. The cause of such emission is the change in the effective resistance of the telephone transmitter T. which, as it causes branch 0 to approach Fig. 1. produces a corresponding emission of radiative energy. It is obvious that the radiative energy will be emitted in waves following the form, amplitude and rate of succession of speech waves, and that during the intervals between the speech waves, the radiation is suppressed.

It is obvious that our method is equally applicable to undamped oscillation systems. The radiation circuit in such systems would be timed as in F ig. 1 with the oscillation circuit. the radiation suppressed as in Fig. 2 and emitted as in Fig. 3. \Vhcther damped or undamped oscillations are used. our method produces radiation in correspondence with speech waves.

\Ve are aware that microphone transmitters located in a branch shunting the secondarv of an oscillation transformer have been used: but in such cases'the radiation circuit. including the b anch. has been tuned to emit the greatest radiation when no talking is taking place. The mode of operation ol such-devices is tointerrupt the continually radiated encrgv. as distinguished from our in. I'ntllillltlll. and sends it out in waves such or rec'ede from the condition illustrated in with speech waves. method. which suppresses directly corresponding with the changes of resistance in the shunt,- which changes are produced by vocally vibrating the microphone transnntter. 1

Because our adiat on is suppressed at the moments when the microphone transmitter is not operating, disturbances due to such radiation at such moments cannot take place. Moments when the microphone transmitter is inactive occur within the compass of spoken words, between the syllables, and in the intervals separating the words. Such moments are normal constituents of speech, andcannot be interfered with if clearness is to be preserved. \Ve claim for our system that it will not interfere with the moments of silence; for even the undamped oscillation systems tend .to interfere when the arc varies in character. We have found that the alternating impulses of. the frequency used in our method have nodetrimental efi'ects on the articulation. It is to be observed that the branch circuit is one practically without inductance. The necessary adjustments of inductances and capacities to secure-the suppression of the'radiation may readily be madcby the adjustable condensers and coils shown in the the drawing; By no radiation it is to be understood an amount of radiation so small as to be negligible. approaching zero near enough 'claim'as new and desire to secure by Letters Patent of the United States,-moclifications within the, scope of the claims being eitpressly' reserved, is: v p

1. A method of transmitting speech by wireless telephony which consists in contin ually producing oscillations in an oscillation circuit, deriving therefrom oscillations the radiation of which is suppressed in a radiation circuit. and emitting radiative energy from said circuit in direct correspondence with speech waves.

2., A method of transmitting speech by wireless telephony which consists in continually producing oscillations in an oscillation circuit. deriving therefrom oscillations in a radiation circuit, suppressing radiation therefrom during moments of silence. and emitting waves of radiative energy in direct correspondence with speech waves.

3. Apparatus for transmitting speech by wireless telephony which consists in an oscillation circuit, means for continuallyproducing oscillations therein, a radiation circui't associated therewith, means for deriving from said oscillation circuit oscillations the radiation of which is suppressed insaid radiation circuit, and means for emitting radiative energy in direct correspondence 4. Apparatus. for transmitting speech by wireless telephony which consists in an oscillation circuit, .means for continually producing oscillations therein, a radiation circuit ing the moments of silence, and means for emitting waves of radiative'energ in direct correspondence withspeech waves.

5. Apparatus for transmitting speech by wireless telephony which consists in a radia tion circuit, an associated continually operated oscillation circuit tuned thereto, a branch circuit for suppressing the radiation from said radiation circuit, and a microphone transmitter in said branch for transmitting radiative energy in correspondence.

with speech waves.

6. Apparatus for transmitting speech by wireless telephony which consists in a'radiation circuit-including a variableinductance coil and a variable condenser, an associated continually operatedoscillation circuit tuned thereto, a branch circuit attached outside the inductance coil and condenser for suppressing radiation from said radiation circuit, and a microphone transmitter in said branch for transmitting radiative energy in correspondence with speech Waves.

7. The method of transmitting sound wireless telephony, which method comprises producing oscillations, normally suppressing radiation of said oscillations, and effecting by sound waves the emission of radiative energy which emission consists of waves corresponding in form, amplitude and rate to said sound waves 8. In combination, an oscillatory circuit, a radiation circuit, means to suppressradiation in the radiation circuit when afi'ected by sound waves to produce emission of radiative energy from the radiation circuit in waves corresponding in form, amplitude and rate to soun waves.

9. In a wireless telephone system, a source from whichalternatin current is produced having a frequency 0 from one thousand to four thousand, means for producin oscillations in an oscillation circuit, a radiation circuit associated therewith, means for suppressing radiations from said radiation circuit, and means for emitting radiative .energy from said circuit in direct correspondence with speech waves.v

In testimony whereof, we have hereunto signed our names in the nesses this 29th day of JOHN P. 'MoCARTY. KENDALL DOUGLAS.

ebruary, 1912 Witnesses FRANK P. MEDINA,

presence of two wit- 

